Having purged a group of rivals, Supreme Leader of North Korea Kim Il Sung delivered the "May 25 teaching", entrenching his son Kim Jong Il as his designated successor.

The Kapsan faction incident was an unsuccessful attempt to undermine the power of Kim Il Sung, the leader of North Korea, around the year 1967. The "Kapsan faction" was a group of veterans of the anti-Japanese struggle of the 1930s and 1940s that was initially close to Kim Il Sung. In the wake of the 2nd Conference of the Workers' Party of Korea (WPK) in 1966, the faction sought to introduce economic reforms, challenge Kim Il-sung's cult of personality, and appoint its leader Pak Kum-chol as his successor.

The supreme leader of North Korea is the de facto hereditary leadership of the Workers' Party of Korea, the state and the Korean People's Army. The title is honorary, given only after death in the first two cases. More broadly it can also refer to the "Supreme Leader system" (Suryeong-je), which is defined as "a system that aims to ensure continuous leadership by the Supreme Leader across generations." Different titles were used in North Korean propaganda that could be translated from Korean as "Great Leader", "Dear Leader", or "Supreme Leader".

Kim Il Sung was a North Korean politician and the founder of North Korea, which he led as its first supreme leader and dictator from its establishment in 1948 until his death in 1994. Afterwards, he was succeeded by his son Kim Jong Il and was declared Eternal President.

Kim Jong Il was a North Korean politician and dictator who was the second supreme leader of North Korea from the death of his father Kim Il Sung in 1994 until his death in 2011, when he was succeeded by his son, Kim Jong Un. Posthumously, Kim Jong Il was declared Eternal General Secretary of the Workers' Party of Korea (WPK).